The work is directed to investigation of the androgen dependent proteins within the chimpanzee epididymis, with the potential for development of contraceptive vaccines. We have identified EP2 as androgen dependent and have identified several different splicing variants of the EP2 gene. The two main variants, EP2A and EP2B, differ in that they are transcribed by different promoters. The N-terminal sequence of both variants possess concensus sequences for a signal peptidase cleavage site, as expected for a secretory protein. Using a genomic clone of EP2, we are int the process of identifying the promoter and any associated androgen-binding sequences. We are currently expressing the EP2 protein in a bacterial system, as antibody generation in rabbits and chickens has been unsatisfactory, to use the expressed protein as antigen. When this antibody is obtained we will continue studies to elucidate the function of EP2 in post-testicular sperm maturation. As a separate part of these studies we have published a detailed report on the immunohistochemical localization of the epididymal secretory protein EP1 in the chimpanzee epididymis.